Turntable drive mechanism



April 20, 1943. E. o. THOMPSON TURNTABLE DRIVE4 MECHANISM Filed Septl 27, 1941 2 Sheets-Sheet 1 April 20, 1943.

E. O. THOMPSONl TURNTABLE DRIVE. MECHANISM Filed Sept. 27, y1941 2 Sheets-Sheet 2 vat Patented Apr. 19.43.

TURNTABLE parvis:,Mncnnmsiirr Elmer 0. Thompson, Gtasmere,'N. Y., assigner to Philco Radio and `'Television Corporation. Philadelphia, Pa., a corporation of Delaware Application September 27, 1941, Serial No. 412,654

' 1 claims. l cL 'I4-194) This ,invention relates to drivemechanisms for phonographs and more particularly to a (phonog'aph'turntable drive mechanism of, the type.

ad pted to provide variable or multi-speed operi of thephonograph.

l )r some time, there has existed a demand for an inexpensive phonograph turntable speed )coni trol capable of simple adjustment to meet widely diieent requirements. For example, it is advantageous to utilize a phonograph having a drive mechanism adapted for operation at two substantially different principal speeds, with a speed control adapted to vary the phonograph speed about 'each of these principal speeds as a mean. It is also desirable that the above noted control functions be performed by a single manually operable member capable of various modes oi operation to selectively perform the control functions.

In accordancewith the foregoing, it is a principal object of the present invention to provide a novel and improved phonograph speed control which will permit operation of the phonograph at two-substantially diilerent speeds.

A further object of the invention is to provide a novel phonograph speed control adapted to vary the phonograph speed about the two principal speeds.

Still another object of the invention is to provide a single manually ioperable control member for a-phonograph, which member is manually adjustableto permit operation of the turntable within two different speed ranges, the selection of the speed range and the selection of the speed within each range being determined by diiferent modes of adjustment of the single control manual.l Another object oi the invention is to provide a phonograph speed control manual of novel character adapted for easy and smooth adjustment to regulate the phonograph speed.

Other objects of the invention will be clear from the following description and claims.

In the drawings:

Fig. 1 is a side elevation of a phonograph drive mechanism constructed in accordance with the present invention;

Fig. 2 is a top plan view of the mechanism j with the base plate and -turntable shown in dotl and dash outline: l

Fig. 3 is a detail sectional view taken along line 33 of Fig. 1; Fig. 4 is a detail sectional view of a drive mechanism;

Eig. 5 is a further detail sectional view taken along line 5-5 of Fig. 4; and

part of the Figs. 6 and 7 are views of a portion of the mechanism illustrating a turntable speed indicator which may be employed.

With reference to the drawings, one form of apparatus constructed according to this invention may comprise a rectangular metal baseplate iI having a circular recessed central portion 2 to accommodate the conventional turntable 3 which may be supported for rotation on base plate I by abearing (notshown). The cooperating phonograph tone arm and amplifier may be of any conventional type and hence no details thereof. need be given here.

Beneath the base plate I a pair of depending arms I (Fig. 1) serve to pivotally mount one end 5 ot a generally horizontal bracket 6. The-other end'of bracket i is supported in a manner to be described so that thev brack'et is rotatable to a small extent about its pivot.

An electric driving motor 1 is' mounted. on bracket 8 by means of semi-resilient bushings I which prevent the vibration of the motorbeing transmitted to the remainder of the mechanism. The axis of the motor drive shaft 9 is generally horizontal and a driving disc I0 is secured at one end of shaft 5.

As is best shown in Figs. 1, 4, and 5, bracket B carries a small U-shaped bracket II which in turn carries a pivotally mounted bearing I2 slidably supporting the lower end of a second shaft I3. The shaft I3 extends upward through a large opening Il in the base plate I. To support the upper end of the shaft I 3, a'lever I5 (Figs. 2 and 4) vis secured beneath base plate I and is arranged for generally longitudinal movement under the influence oi' a spring I6 and for rotary movement about a stud l'lby a spring I8. At.

its free end lever I5 has a cup shaped depression I3 (Fig. 4) through which the shaft I3 passes.

An oilless bearing 20 is seated in the cup I9 and is prevented from rotating by a lug 2| Iwhich extends into a recess in bearing 20. At the upper end of shaft I3 there is a rubber covered driving pulley 22. Below lever I5 a collar 23 is mounted on shaft I3. Collar 23 and pulley 22 serve to prevent longitudinal movement of shaft I3 relative to lever i5 yet the construction is such that shaft I3 is properly supported for rotation while permitting a slight rocklngof theshaft I3 and its bearing 2|). The pulley 22 is urged into contact with the. inner edge of a right angle ilange 24 on the edge of turntable 3 b y theA springs I6, I8 (Fig. 2), and a stop Ia limits the counterclockwise rotation of lever I5. A generally bell shaped pulley 25 (Fig. 4) having a rubber cov- *ered aange :s 'is bearing 'will now be explained.'

.bracket Ito support a secured toI shaft Il. over the i2 so that its i'lange 2| will bear against the driving face of the disc il. Athrust bearing 21 on the motor 1 lcontinuously urges shaft I toward the left (as shown in Fig. 1) to maintain contact between the vdisc l and pulley 25. By

. the structure thus far described. a driving con-l nectlon between motor land turntable 3 is provided.. Certain features of' this structure are Vdescribed-ane claimed in the copendxng application of C. BpDale. Serial No. 416.418, filed October 24, 1941-, and form novpart of the present invention.

The construction and arrangement of disc Il and pulley 2l is such that the speed of rotation of the turntable point of contact between them,`

2 will be determined by the ing radius on disc It the pivotally mounted bracket i is adjustable between the positions shown in the lull and dotted lines of Fig. 1, as

A bracket 28 is mounted above theiree end 29 of pivotally mounted bell crank It. The end of one arm of crank 30 is pivotally secured to an end of link'ILvthe other end of which is secured to the end 29 of bracket i through a resilient bushing l2. The other arm beneath base plate i .of crank 3l carries two spaced parallel lugs 23 which are slotted to receive a small diameterwardly through the base plate slot and escutcheon Il and at its upper end it carries a round -bottomed knob 38. However, as shown in Fig. 3. the rod 34 and knob l2, are yeccentrically joined. A coil spring 39 is arranged to firmly seat knob lt on escutcheon 3i. Spring ll surrounds rod 34 and its upper end engages the upper lug I3 while its lower end engages a small collar or iiange aflixed to rod 34. The spring is under compression so that it urges rod 34 downward to seat knob 2l. 'A spring 4 0 takes up the play between the lower end of rod 3l' and the lower lug Certain features of the above construction are related lto the copending application of W. J. Green, Serial No. 411,435, iiled September 18, 1941.

With the above construction it will be seen that the knob $2 has two normal positions which are determined by the openings l1. Movement of knob il, after raising it slightly against the action oi' spring Il, from oneposition to the other will cause rotation of the bell cranklll about its pivotand link Il will motion to bracket.. which will rotate about its pivot so fthat the driving radius of disc Il will be changed. Thus the turntable speed can be quickly varied from one speed to another by moving knobV Il from one. position to another.

The'linkages are preferably. so designed that the turntable speed can be changed from full to haii speed by this arrangement, full speed being about '18 It. P. H. 1

transmit this' l31, it is onlynecessary while leaving it in one of its positions. `By'virtue In about the mean speed determined by the positioning of the knob 38 of the eccentric rod to knob connectiomrota- .tion of openings 31 will cause' the rod u to' rock the bell crank ll about its pivot,'t.hus providing a small range of'adjustment`for the bracket 6. Since in thisinstance the central axis of rotation of knob il remains stationary,`the upper portion of the rod is rotated through asmall `that is, the lgreater the driving radius of disc il the greater will. be the turntable' speed. To vary this drivto accurately determine in a round opening 31. Rod 3l extends upwithout departing from this invention as this; Since the flange,

circle about the axis oi knob It. 'I'he loose mounting of the lower end oi' the rod permits upper portion of' rod 3| can move relative to the upper. lug only longitudinally or! slot 33a, its rotation causes the bell crank 30, to rock about its pivot.

ly means of this novel constnuction the knob 38 serves to establish the general range of the turntable speed and also to provide a VVernier the turntable speed within that range.

A normally `iixed adjustment such as' the nuts Il on link 3| may be used as the initial speed setting means -to initially adjust the bracket 8.'

To indicate the turntable speed," the flange of the turntable is provided' with a predetermined number of markings 42 (Fig. '1). Beneath the-base plate I a lamp l uch .as a neon bulb energized from an alternat ng current source, is provided, and adjacent the lamp a small opening M is provided in the verticalwall of the depression 2 (Fig. 6). Light from the lamp shines through the opening onto the turntable the lamp and the markings on the turntable forming a stroboscope to indicate the turntable speed. Preferably the number of the markv the stroboscope will indicate ings 42 issuch that l isibeing driven at full and when theturntable half speed.

The above described apparatus makes possible accurate control of the phonograph with a simpie mechanism. The two speed operation of the turntable for the reproduction of diil'erent recordings and the uniform speed operation during both recording .and reproducing are obviously very desirable. Further by initially adjusting the nuts Il the same turntable speed can be obtained withthe motor 1 connected to power supplies of different frequencies (such as 50 and cycles) it being only necessary to use a different escutcheon 35 and dinerent turntable markings 42 to obtain accurate half speed operation and proper indication or the turntable speed, as will be understood. l y

Of course, the above described drive mechanism can be used on either manual or automatic phonographs or on phonographs including an automatic record changing mechanism of any suitable type. Further, it is clear that the apparatus. described is capablev 'of modiiicatlon deiined in the appended claims.

I claim:

1. In a turntable speed control device. for. a

order to vary the speed ot the turntable in one of the openings -to rotate the knob 38 v knob 3l while it is seated in one of the n and being constrained for movement relative to said member in a plane generally parallel to the axis of rotation thereof. whereby rotation of said manual will cause adjustment of said member positions, a member attached to said control element eccentrically of its axis, means for maintaining the axis of said element stationary while it is in one of said positions, a pivoted bellcrank operatively associated with said member for actuation thereby in response to the diierent movements of said control element, and means operable by said bell crank for adjusting said drive means.

3. In-a drive mechanism for a phonograph, variable speed drive means, a manual control element arranged for translational movement between different positions and for rotary movement about its axis when disposed in one of said positions, a member attached to said control element eccentrically of its axis, means for maintaining the axis of said element Stationary while it is in one of said positions, a pivoted bell crank having apertured portions through which said member extends,'said portions being constructed and arranged to effect actuation of said bell crank in response to the different movements of said control element, and means operable by said bell crank for adjusting said drive means.

4. In a drive mechanism for a phonograph, a vertical shaft to be driven, a wheel on said shaft, a generally horizontal pivoted bracket', a pivoted bearing on s aid bracket in whichone end'of said shaft is slidably journaled, driving means on saidv bracket including a atdriving' disc having its face in driving engagement with the edge of said wheel, and manually adjustable means for moving said bracket about its pivot to vary the driving radius of said disc.

5.- InV a drive mechanism for a phonograph, a

4vertical shaft to be driven, a wheel on said shaft,

a generally horizontal pivoted bracket, a pivoted bearing on said bracket in which one end of said shaft is slidably journaled, driving means on said bracket including a at driving disc having its face in driving engagement with the edge of said wheel, a manual control memberarranged for translational movement between different positions and for rotational movement when in one of said positions, and means operable by said member during'either movement of the same for moving said bracket about its pivot to vary the driving radius of said disc.

6. In a phonograph drive mechanism, variable speed drive means including a vertically adjustable element, a control member arranged for translational movement between two horizontally spaced positions and for rotational movement when in either of said positions, and means for eiecting vertical movement of said element in response to either -movement of said control member; whereby said drive means is quickly adjustable to different principal speeds corresponding to said positions and is also accurately adjustable to speeds about the principal speeds.

7. In a phonograph drive mechanism, variable speed drive means including a vertically adjustable element, a control member including a man.- ual knob arranged for translational movement between two horizontally spaced positions and for rotational movement when in either of said positions, guiding and retaining means for said member having a slot with enlarged ends for 

